What do systematic reviews say?

Dental cavity liner (e.g. calcium hydroxide, glass ionomer, resin-modified glass ionomer, or flowable composite) placed under the restoration vs No cavity liner or a different liner material

Cavity liners may make little or no difference to tooth survival (99.4% survival across groups; low certainty).

• Efficacy of different cavity liners compared to no cavity lining in managing deep caries in vital permanent teeth - a… 2025 All outcomes

  >=12 months · Dental clinical settings (multiple countries)
  No significant difference; 99.4% survival in all groups
  12 studies · 1184 participants
  Low

PET-CT following chemoradiotherapy (neck dissection only if no/incomplete response) vs Planned neck dissection before or after chemoradiotherapy

• Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment 2023 · Cochrane All outcomes
  Disease-free survival: outcome not reported in a usable way (Mehanna 2017: disease-specific and other-cause mortality did not differ, P=0.80 and 0.41).
  1 study
  GRADE not reported

Hyperbaric oxygen (following replantation) vs control

It is very uncertain whether hyperbaric oxygen (following replantation) changes tooth survival at 12 months compared with control (very low certainty).

• Interventions for treating traumatised permanent front teeth: avulsed (knocked out) and replanted 2019 · Cochrane All outcomes

  12 months
  RR 1.21 [1.07, 1.36]
  1 study · 69 participants
  Very low

CAD/CAM nitinol fixed (bonded) retainer vs Multistrand / spiral wire fixed (bonded) retainer

It is very uncertain whether CAD/CAM nitinol fixed (bonded) retainer changes survival of retainers (failure, lower arch) compared with conventional/analogue multistrand fixed (bonded) retainer (very low certainty).

• Retention procedures for stabilising tooth position after treatment with orthodontic braces 2023 · Cochrane All outcomes

  12 months · lower arch
  RR 1.29 [0.67, 2.49]
  1 study · 41 participants
  Very low

Full-time clear plastic (removable) retainer vs Any type of fixed (bonded) retainer

It is very uncertain whether full-time clear plastic (removable) retainer changes survival of retainers (failure, lower arch) compared with any type of fixed (bonded) retainer (very low certainty).

• Retention procedures for stabilising tooth position after treatment with orthodontic braces 2023 · Cochrane All outcomes

  12 months · lower arch
  RR 3.42 [1.38, 8.47]
  1 study · 77 participants
  Very low

Fibre-reinforced composite fixed (bonded) retainer vs Multistrand / spiral wire fixed (bonded) retainer

Fibre-reinforced composite fixed (bonded) retainer showed no clear difference in survival of retainers (failure, lower arch) compared with multistrand / spiral wire fixed (bonded) retainer (low certainty).

• Retention procedures for stabilising tooth position after treatment with orthodontic braces 2023 · Cochrane All outcomes

  12 months · lower arch
  RR 1.01 [0.84, 1.21]
  7 studies · 1337 participants
  Low

Part-time clear plastic (removable) retainer vs Any type of fixed (bonded) retainer

It is very uncertain whether part-time clear plastic (removable) retainer changes survival of retainers (failure, lower arch) compared with any type of fixed (bonded) retainer (very low certainty).

• Retention procedures for stabilising tooth position after treatment with orthodontic braces 2023 · Cochrane All outcomes

  12 months · lower arch
  RR 0.44 [0.20, 0.98]
  1 study · 57 participants
  Very low

Fibre-reinforced composite fixed (bonded) retainer vs Multistrand / spiral wire fixed (bonded) retainer

The review found no eligible studies for this question.

• Retention procedures for stabilising tooth position after treatment with orthodontic braces 2023 · Cochrane All outcomes

  12 months · lower arch
  No RCTs at 12-month follow-up; 2 RCTs at 24 months: earlier failures with fibre-reinforced composite (MD -1.48, 95% CI -1.88 to -1.08; very low-certainty)
  0 studies
  No studies found

Hawley removable retainer vs Clear plastic removable retainer

It is very uncertain whether hawley removable retainer changes survival of retainers (failure, upper and lower arches) compared with clear plastic removable retainer (very low certainty).

• Retention procedures for stabilising tooth position after treatment with orthodontic braces 2023 · Cochrane All outcomes

  12 months · upper and lower arches
  RR 0.60 [0.43, 0.83]
  1 study · 111 participants
  Very low

Surgery +/- radiotherapy + (adjuvant) chemotherapy vs Surgery +/- radiotherapy alone (observation or adjuvant radiotherapy only)

Surgery +/- radiotherapy + (adjuvant) chemotherapy showed no clear difference in overall survival, adjuvant chemotherapy vs observation alone… compared with surgery +/- radiotherapy alone (observation or adjuvant radiotherapy… (moderate certainty).

• Interventions for the treatment of oral cavity and oropharyngeal cancer: chemotherapy 2021 · Cochrane All outcomes
  HR 0.95 [0.73, 1.22]
  5 studies · 353 participants
  Moderate

Polaprezinc vs Azulene oral rinse

• Pharmacological interventions for preventing dry mouth and salivary gland dysfunction following radiotherapy 2017 · Cochrane All outcomes
  Tumour response by RECIST criteria reported for a specific group of patients only; no usable survival data (Watanabe 2010)
  1 study
  GRADE not reported

Biperiden plus pilocarpine vs no treatment

The review found no eligible studies for this question.

• Pharmacological interventions for preventing dry mouth and salivary gland dysfunction following radiotherapy 2017 · Cochrane All outcomes
  Survival not reported.
  0 studies
  No studies found

Bethanechol vs placebo

The review found no eligible studies for this question.

• Pharmacological interventions for preventing dry mouth and salivary gland dysfunction following radiotherapy 2017 · Cochrane All outcomes
  No survival data were reported.
  0 studies
  No studies found

Selenium vs no intervention

The review found no eligible studies for this question.

• Pharmacological interventions for preventing dry mouth and salivary gland dysfunction following radiotherapy 2017 · Cochrane All outcomes
  No survival data were reported.
  0 studies
  No studies found

Antimicrobial lozenge vs placebo

The review found no eligible studies for this question.

• Pharmacological interventions for preventing dry mouth and salivary gland dysfunction following radiotherapy 2017 · Cochrane All outcomes
  No survival data were reported.
  0 studies
  No studies found

Antiseptic mouthrinse vs placebo

The review found no eligible studies for this question.

• Pharmacological interventions for preventing dry mouth and salivary gland dysfunction following radiotherapy 2017 · Cochrane All outcomes
  No survival data were reported.
  0 studies
  No studies found

Bethanechol vs Artificial saliva

Bethanechol showed no clear difference in overall survival compared with artificial saliva; GRADE not reported.

• Pharmacological interventions for preventing dry mouth and salivary gland dysfunction following radiotherapy 2017 · Cochrane All outcomes

  40 weeks postRT
  RR 1.59 [0.43, 5.84]
  1 study · 43 participants
  GRADE not reported

Keratinocyte growth factor (KGF; palifermin or repifermin), intravenous vs placebo

Palifermin showed no clear difference in overall survival compared with placebo (moderate certainty).

• Pharmacological interventions for preventing dry mouth and salivary gland dysfunction following radiotherapy 2017 · Cochrane All outcomes

  42 to 72 months from baseline
  HR 1.00 [0.72, 1.39]
  3 studies
  Moderate

Amifostine (intravenous) vs Amifostine (subcutaneous)

Amifostine (intravenous) showed no clear difference in overall survival compared with amifostine (subcutaneous); GRADE not reported.

• Pharmacological interventions for preventing dry mouth and salivary gland dysfunction following radiotherapy 2017 · Cochrane All outcomes

  48 months postRT
  HR 1.36 [0.89, 2.10]
  1 study
  GRADE not reported

Pilocarpine vs no treatment/placebo

It is very uncertain whether pilocarpine changes overall survival compared with no treatment/placebo (very low certainty).

• Pharmacological interventions for preventing dry mouth and salivary gland dysfunction following radiotherapy 2017 · Cochrane All outcomes

  Up to and including 6 months postRT
  RR 1.07 [0.80, 1.43]
  1 study · 60 participants
  Very low